Italy's National Research Council said the 97-year-old Dulbecco died Monday in California, the Italian news agency ANSA reported.
Dulbecco was a founding fellow of the Salk Institute for Biological Studies in La Jolla, where he had been a distinguished professor.
Dulbecco shared the Nobel Prize with Howard M. Temin and David Baltimore of the United States "for their discoveries concerning the interaction between tumor viruses and the genetic material of the cell."
The research offered the first clue to the genetic nature of cancer, demonstrating how a virus could insert its own genes into the chromosome of the cell it infects and spark cancer's uncontrolled growth.
Notable deaths of 2014 [PHOTOS]